I've been lamenting the lack of shelving in my pantry and wardrobe for the last couple years but didn't think I could do anything about it without going to kitchen and wardrobe specialists. Then one day I got the bright idea to take out a couple of the inserts, trot them down to the hardware store and get additional shelves cut to the same size. So now I have 2 extra shelves in my pantry, 4 extra shelves in our wardrobe, and heaps more storage space.
I don't know why it took me 3 years to figure out that I could do that! Duh.